Representing Sparse Data in PostgreSQL
What's the best way to represent a sparse data matrix in PostgreSQL? The two obvious methods I see are:
Store data in a single a table with a separate column for every conceivable feature (potentially millions), but with a default value of NULL for unused features. This is conceptually very simple, but I know that with most RDMS implementations, that this is typically very inefficient, since the NULL values ususually takes up some space. However, I read an article (can't find its link unfortunately) that claimed PG doesn't take up data for NULL values, making it better suited for storing sparse data.
Create separate "row" and "column" tables, as well as an intermediate table to link them and store the value for the column at that row. I believe this is the more traditional RDMS solution, but there's more complexity and overhead associated with it.
I also found PostgreDynamic, which claims to better support sparse data, but I don't want to switch my entire database server to a PG fork just for this feature.
Are there any other solutions? Which one should I use?
I would like to develop a multi-tenant web application using PostgreSQL DB, having the data of each tenant in a dedicated scheme. Each query or update will access only a single tenant scheme and/or th
Why aren't there any multidimensional sparse matrices/arrays in Julia? Why can we only have 2D sparse matrices and not for example 3D sparse matrices (or arrays)?
I have three integer values. I need to represent these data as a chart. What should i do. Will iReports be the right option. If so give some pointers to tutorials for the IReports.
it's been a while since I have made one of my Converting MySQL to PostgreSQL posts. So, today's problem is as follows: The original MySQL queries involve where clauses which look a bit like the foll
I need to store the geographic location of a few physical locations in my Grails/GORM/PostgreSQL based software. Not a whole lot (about a 100), and there won't be any geo-spatial searches or calculat
When representing graphs in memory in a language like Java, either an adjacency matrix is used (for dense graphs) or an adjacency list for sparse graphs. So say we represent the latter like Map<Int
I wrote the following code to represent JSON data in C++. I got some vague review comments that this may not be optimal and if we decide to parse JSON data directly into this structure then we might h
I am using PostgreSQL on Mac, I have created several databases using command line. I am looking into /Library/PostgreSQL/9.2/data and I can not see any .dat file. Am I looking into the wrong place for
I am new to postgresql (and databases in general) and was hoping to get some pointers on improving the efficiency of the following statement. I am inserting data from one table to another, and do not
I have an assignment where Im supposed to finish the implementation on a generic sparse matrix. Im stuck on the addition part. The matrix is only going to support numbers so I had it extend Number hop
I'm trying to fetch data from PostgreSQL with Erlang. Here's my code that gets data from DB. However i have cyrrilic data in 'status' column. This cyrrilic data is not being fetched correctly. I tried
Suppose you have a data frame with a high number of columns(1000 factors, each with 15 levels). You'd like to create a dummy variable data set, but since it would be too sparse, you would like to keep
I have a large sparse graph that I am representing as an adjacency matrix (100k by 100k or bigger), stored as an array of edges. An example with a (non-sparse) 4 by 4 matrix: 0 7 4 0 example_array = [
i Just want to write a script which finds the tables in a particular postgresql data and converts/exports whole data to individual csv files help me in starting with sample scripts in postgresql
I have a PostgreSQL table with the following schema - CREATE TABLE test ( id serial NOT NULL PRIMARY KEY, username varchar(100) NOT NULL, -- The user name dob timestamp with time zone NOT NULL -- The
I created a compressed sparse matrix, but while accessing to a positive index it complains that the index is negative: import scipy.sparse as sparse B= sparse.csc_matrix((110111213141516, 25)) B[11011
I would like to manipulate matrices (full or sparse) efficiently with haskell's vector library. Here is a matrix type import qualified Data.Vector.Unboxed as U import qualified Data.Vector as V data L
I need to compile a binary file in pieces with pieces arriving in random order (yes, its a P2P project) def write(filename, offset, data) file.open(filename, ab) file.seek(offset) file.write(data)
This question already has an answer here: Migrate database from Postgres to MySQL 2 answers I'm looking to grab a few bits of data from musicbrainz db to use in a mysql based app. I don't need
I am searching for a query which can group similar data into one column. Basically, I have a table which is representing an order item. Each order item belongs to an order. An order item has an amount
Suppose I have a sparse matrix Sparstica that is a vertical concatenation of several other sparse matrices. When I type Sparstica(:), I get a list of the nonzero elements. In the left column, will be
Imagine a table with the following structure on PostgreSQL 9.0: create table raw_fact_table (text varchar(1000)); For the sake of simplification I only mention one text column, in reality it has a do
I am trying to multiply two large sparse matrices of size 300k * 1000k and 1000k*300k using Eigen. The matrices are highly sparse ~0.01% non zero entries, however there's no block or other structure i
i searched many ways but i didn't get the information about how to write the data to a file when call the database function (postgresql) in the java program.. please clarify me on this.... thanks in a
I do not have access to third party components on this project. I think I only have access to the built-in DataGrid and GridView controls. Is there a good example for representing hierarchical data (i
Today I installed postgreSQL to work with. When I was reading documents about postgreSQL, I found there can be more than one data directory present. Is it more than one data directory for single insta
I am attempting to insert parsed dta data into a postgresql database with each row being a separate variable table, and it was working until I added in the second row recodeid_fk. The error I now ge
Inserting data into PostgreSQL database with iBATIS is not working and not giving any exception. Please help me to get out of this. This code is working some time but not every time. And code is prope
I want to read binary data from disk and store it in a Mercury variable. According to the string library, strings don't allow embedded null bytes and store content with UTF-8 encoding so I don't think
I'm trying to generate a stacked column chart. What I want is similar to this JSfiddle example. However, I have around 30 categories and 1000 series. The series are rather sparse. There are only about
Update: I could have formulated this question in abstract terms, but this way it would be less illustrative. So please don't downvote it for being too specific. I need to come up with a data structure
Here is my data: client_addr | start ------------+----------- 188.8.131.52 | 12:54:06 184.108.40.206 | 12:55:00 220.127.116.11 | 12:54:06 18.104.22.168 | 13:00:00 22.214.171.124 | 11:00:00 126.96.36.199 | 14:00:00 I want to sort it and r
I'm trying to use large 10^5x10^5 sparse matrices but seem to be running up against scipy: n = 10 ** 5 x = scipy.sparse.rand(n, n, .001) gets ValueError: Trying to generate a random sparse matrix su
I have installed Postgresql 9.2 and would like to use LTREE data type. When I try to create table as in the documentation. CREATE TABLE test (path ltree); I have error: type ltree does not exist I us
While attempting to combine dense and sparse data with scipy.spare.hstack, I'm occasionally running into the error: Traceback (most recent call last): File hstack_error.py, line 3, in <module>
I am trying to query a table with a column with the postgresql array data type in Rails 4. Here is the table schema: create_table db_of_exercises, force: true do |t| t.text preparation t.text ex
How would one go about storing and querying sparse directed or undirected graphs in Postgresql. There is something like pggraph, but that is still in planning stage. I realize dedicated graph database
I have a large corpus of data (text) that I have converted to a sparse term-document matrix (I am using scipy.sparse.csr.csr_matrix to store sparse matrix). I want to find, for every document, top n n
I am new to cassandra. In cassandra,in order to store cores we do specify the local directory of cassandra installed machine using the property data_file_directories in Cassandra.yalm configuration fi
I have a text file that contains data in the following format: char char char char #1 a b c char char char dateTime #2 d e 20-12-2012 #3 g h 8-12-2013 I have created 2 tables in PostgreSQL: one with
I'm trying to take the dot product of a row in a sparse matrix with the transpose of that row using Python. I have a huge sparse matrix called X2. And I am saving the results (which is supposed to be
In working with some text data, I'm trying to join an np array(from a pandas series) to a csr matrix. I've done the below. #create a compatible sparse matrix from my np.array. #sparse.csr_matrix(X['l
I have a table on a PostgreSQL server database with almost 3 million rows and I need to save all rows to a CSV file. The problem here is that the rows must be saved in a different random order each ti
how to import data *.xml(taken from sql server) To PostgreSQL 9.3..Already create table with same column XML.now problem to maping data.any help. thanks you
I am new to Hyperion Essbase. What is the difference between a SPARSE and DENSE Dimension? Is there any documentation that could help me with this?
I have found plenty of online and print guides on how to tune and optimize performance for Postgres for OLTP applications, but I haven't found anything of the sort specific to Data Warehousing applica
I've just installed ArcGIS Server Enterprise Advanced with ArcSDE and PostgreSQL, on a virtual Windows Server 2008 box. After installing, I've been trying to import a feature class (stored in a shapef
I'm trying to backup all the content from my postgresql database. I have 2 sites my live one and the dev one. All the code is in sync i just want to copy all the data across to the dev site to do some
I've got a simple java main which must write bean data on a PostgreSQL database. I use Entity manager to persist or update object. I use hibernate and toplink driver connection which are specified in
I'm planning a side project where I will be dealing with Time Series like data and would like to give one of those shiny new NoSQL DBs a try and am looking for a recommendation. For a (growing) set of